Akihabara News: Buffalo’s DH-ONE/IP is a digital TV tuner dongle for your iDevice. There are some critical limitations though. First, it is a digital TV tuner that works with 1-Seg, a digital TV network in Japan. Second, you need an iPhone 4 or 3GS, iPod touch 3rd Gen with iOS 4.0, or an iPad running iOS 3.2.
Looking at the photo I’m not sure I’d want to be seen with such a dongle hanging from my iPhone or iPad. A better idea might be a case with a built-in (stealthy) digital TV tuner.